Direction finding device



Dec. 4, 1951 M. ERCOLINO DIRECTION FINDING DEVICE Filed Sept. 2, 1949 FIG.2

IHIIII FIG.4

I8 16 V 1a INVENTOR.

MICHAEL ERCOLINO A TTORNEY Patented Dec. 4, 1951 DIRECTION FINDING DEVICE Michael Ercolino, Wanamassa, N. J., assignor to the United States of America as represented by the Secretary of the Army Application September 2, 1949, Serial No. 113,891 14 Claims. (Cl. 343-113) (Granted under the act of March 3,1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

The present invention relates to improvements in.,the art of direction findingand sensing equipment and methods, and is a device that can be attached to a radio receiver for determining the direction to any transmitter of radio frequency energy at the frequency to which the receiver is tuned provided that the receiver is within the effective range of the transmitter.

The object of this invention is to provide a very simple and readily portable direction finding antenna of reasonable accuracy.

It is a further object of this invention to provide a manually operated dipole antenna, providing two response patterns.

It is a further object of this invention to provide a wide band, dipole antenna with means for producing both a figure of eight and a cardioid v response pattern. This invention is particularly applicable for use with the Signal Corps receiver SCR-300 to provide direction finding and sensing without appreciably decreasing the portability of the set.

Fig. 1 of the accompanying drawings shows the general physical appearance of the apparatus used in connection with applicant's invention;

Fig. 2 shows the structure and wiring of the device in detail, the antenna and associated receiver being shown only in part to save space;

Figs. 3 and 4 show the thumb switch in cross section.

The apparatus as shown in Fig. 1 consists of the other end of this center element being connected to the antenna socket l2 of the radio receiver 6. The other element 4 of the dipole connects through metal'support 23, and through switch 5 to the shield l3 of the coaxial cable ill. the other end of the shield connecting to the ground terminal l4 of the radio receiver 6 by a connector l5.

Figs. 3 and 4 show the switch 5 in cross section. The switch is in its normal, closed position in Fig. 3 and is open, as if depressed, in Fig. 4. The

switch 5 consists of a flat metal plate It having a hole I! through which a metal button l8, carried by a flat spring is projects slightly. The flat spring [9 is connected to element 4 through the metal support 23 and the plate It is connected to the shield l3 of the coaxial cable ll. When at rest, the metal button I8 is connected to the plate l6 as in Fig. 3, thereby connecting the dipole element 4 to the shield I 3 of coaxial cable I I. When the metal button is depressed, as in Fig. 4, the circuit between button i8 and plate I6 is open.

The switch 5 is placed so as to be conveniently depressed by the operators thumb and is so designed that, while the switch is depressed, the operators thumb forms a resistance connection between the button It and the plate It. At the same time, t e antenna efiect of the operators body is added to the ground input of the receiving set 6 through the metal button and cable.

These changes alter the effect of dipole element a handle I supporting a mounting dielectric framework 2 that supports the two antenna elements 3 and 4 of a folded dipole, and a thumb switch 5. The handle I is used to manually hold this antenna device and to rotate it in any desired direction. This handle is also mountable on the radio receiver 6 by means of a bracket 1 so that it can be held in any desired direction while an azimuth reading is taken.

The dipole elements 3 and 4 are adjustable in length, and are calibrated for setting to one-quarter wave length of the signal to be received, within the limits of the bands of frequencies to be covered. These dipole elements 3 and 4 are arranged to a broad based V formation with approximately a 60 included angle. This provides a wider band coverage than a normal dipole would give and provides maximum receptivity of vertically polarized signals. A coaxial cable I0 is attached from framework 2 to bracket 1 which serves also as a connector to receiver 6.

The circuit connections and their physical inter-relation are seen in Fig. 2 which shows the reverse side of Fig. 1. In Fig. 2, one element, 3, of the dipole connects through metal support 22 to the center element ll of the coaxial cable It,

4 and the input to the radio receiver. When the switch is depressed by a thumb the response pattern is a cardioid, with maxmium signals in the plane of the dipole elements in the direction of the dipole element that has no switch and a minimum in the opposite direction. For convenience in sensing the framework may have an arrow 20 or similar marker which indicates the general direction of the transmitting station for a maximum signal. When the switch is released the response pattern is a figure 8 with a null of receptivity in each direction normal to the plane of the element. For accurate direction finding, sighting means 2| is provided, the angle of this sighting means being accurately adjusted to correspond to the null.

When the apparatus is rotated without the switch depressed, while a signal is being received, two nulls of receptivity are apparent. These are sharp nulls that define the direction of the transmitter within a few degrees. However, this does not indicate in which of the two null directions the transmitter lies.

Sensing the true direction of the transmitter is accomplished by depressing the switch to determine the approximate direction of maximum receptivity, which distinguishes the correct null and avoids ambiguity in determining the azimuth of the transmitter.

The sensing arrangement alone could serve for direction finding, except that the cardioid pattern has neither a sharp maximum nor a sharp minimum of receptivity. Therefore it'is desirable to use the arrangement that produces the figure of 8 pattern, that has sharp nulls, for an accurate direction determination.

In operation, the apparatus is connected to an appropriate receiver, one version of this appa-.

tion as indicated by the arrow approximates the previously determined null direction in which the transmitter lies.

Having actually established the direction of the .transmitter, a more precise azimuth can be determined by mounting the apparatus on the attached bracket above the calibrated azimuth scale 25 and reading, at the null of reception, the azimuth in the direction of the transmitter previously determined.

What is claimed is:

1. A direction-finding antenna device comprising, two antenna elements combining to form a dipole antenna, each of said elements being respectively coupled to an input terminal of a radio receiving apparatus, and a switch, one of said antenna elements being coupled through said switch to its respective terminal, said switch upon being operated serving to include a resistance in series with said one element.

2. A device as in claim 1, wherein said switch is normally closed.

3. A direction-finding device as in claim 1,

wherein said antenna elements respectively have a length of one quarter of the wave length bein received.

, 4. A device as in claim 3 wherein each of said antenna elements consists of a plurality of concentric metal tubes that are collapsible into the said metal tubes.

5. A device as in claim 4 wherein each of said collapsible concentric metal tubes is calibrated to indicate the lengths of said antenna elements near the limit of their extension.

6. A direction-finding antenna device comprising, two antena elements combining to form a dipole antenna, each of said elements being respectively coupled to an input terminal of a radio receiving apparatus, a normally closed switch, one of said antenna elements being coupled through said normally closed switch to its respective terminal, said switch opening to include a resistance, and a dielectric frame, the base of each of said antenna elements being mountedpn said dielectric frame.

7. A device as in claim 6 with a handle at- 4 with a slightly projecting metal button, said metal disc serving to complete the electrical connection between said one element and its respective terminal.

11. A device as in claim 10 wherein depressing of said metal button by an uncovered human digit opens the electrical contact between said metal disc and said respective terminal, whereby body resistance is placed in series with said metal disc and said one element.

12. A direction finding device as in claim 6, said switch being mounted on said frame and consisting of a metal button connected to a metal washer-like disc, said disc being connected to one end of a fiat metal spring, the other end of said spring being connected to the base of said one element, said flat spring serving to urge said washer-like disc in electrical contact with said respective input terminal of said radio receiving apparatus.

13. A device as in claim 12 with a coaxial cable attached to said dielectric frame, the shield of said coaxial cable being connected through said switch to said one antenna element, the center conductor of said coaxial cable being connected directly to the other of said antenna elements, the other ends of the conductors of said coaxial cable being respectively connected to said input terminals of said radio receiver.

14. A device for determining the direction of a radio transmitter using a radio receiver of appropriate frequency response, comprising two one-quarter wave adjustable dipoles mounted on a rotatable dielectric frame, one of said dipoles forming an antenna and connecting to the antenna terminal of said radio receiver, the other of said dipoles connecting through a switch to the ground terminal of said radio receiver, said switch consisting of a flat metal spring, and a metal button connected to and proiecting slightly above the surface of a wa her, said spring being connected at one end to said other of said dipoles and being in electrical contact with said washer at the other end thereof, said washer being urged in electrical contact with said ground terminal by said spring. whereby said antenna maybe rotated with said button of said switch depressed by an operators bare thumb which introduces the resistance of said thumb across said switch and adds the antenna effect of the operators body to said other of said dipoles, the direction of maximum signal indicating the ap proximate direction of said transmitter, said switch then being released and said antenna rotated until a sharp null is observed in said direction of maximum receptivity with the switch depressed, said shar null indicating the exact direction 01' the transmitter.

MICHAEL ERCOLINO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 1,834,274 Fisher Dec. 1, 1931 2,259,628 Fener et al Oct. 21, 1941 OTHER REFERENCES Short Wave and Television for January 1937, page 537.

Radio Craft for November 1939, page 284.

QS'I' July 1946, page 67. 

